Problem: Constraints

* H is an integer between 2 and 50 (inclusive).
* W is an integer between 2 and 50 (inclusive).
* s_{i, j} is `.` or `#` (1 \leq i \leq H, 1 \leq j \leq W).
* s_{1, 1} and s_{H, W} are `.`.

Input

Input is given from Standard Input in the following format:


H W
s_{1, 1}s_{1, 2}s_{1, 3} ... s_{1, W}
s_{2, 1}s_{2, 2}s_{2, 3} ... s_{2, W}
:   :
s_{H, 1}s_{H, 2}s_{H, 3} ... s_{H, W}


Output

Print the maximum possible score that Snuke can achieve, or print -1 if the game cannot be completed.

Examples

Input

3 3
..#
#..
...


Output

2


Input

3 3
..#
..
...


Output

2


Input

10 37
.....................................
...#...####...####..###...###...###..
..#.#..#...#.##....#...#.#...#.#...#.
..#.#..#...#.#.....#...#.#...#.#...#.
.#...#.#..##.#.....#...#.#.###.#.###.
.#####.####..#.....#...#..##....##...
.#...#.#...#.#.....#...#.#...#.#...#.
.#...#.#...#.##....#...#.#...#.#...#.
.#...#.####...####..###...###...###..
.....................................


Output

209

Solution (in JAVA):

Solution:
import java.awt.Point;
import java.io.PrintStream;
import java.util.ArrayDeque;
import java.util.Deque;
import java.util.Scanner;

public class Main {
	final static PrintStream so = System.out;
	final static Scanner sc = new Scanner(System.in);

	public static void main(String[] args) {
		int h = sc.nextInt();
		int w = sc.nextInt();
		char[][] field = new char[h][w];
		int [][]     d = new  int[h][w];
		
		int countDots = 0;
		for (int i = 0; i < h; i++) {
			String line = sc.next();
			
			for (int j = 0; j < w; j++) {
				field[i][j] = line.charAt(j);
				if (field[i][j] == '.') countDots++;
			}
		}
		
		int[] my = {0, 1, 0, -1};
		int[] mx = {1, 0, -1, 0};
		 
		Point start = new Point(0, 0);
		Point goal  = new Point(w-1, h-1);
		Deque<Point> deq = new ArrayDeque<>();
		deq.add(start);
		d[start.y][start.x] = 1;
		
		
		while(!deq.isEmpty()) {
			Point current = deq.poll();
			
			for (int i = 0; i < my.length; i++) {
				int ny = current.y + my[i];
				int nx = current.x + mx[i];
				
				if (ny < 0 || ny >= h || nx < 0 || nx >= w) continue;
				if (field[ny][nx] == '#') continue;
				if (d[ny][nx] != 0) continue;
				
				d[ny][nx] = d[current.y][current.x] + 1;
				deq.add(new Point(nx, ny));
			}
		}
		so.println(d[goal.y][goal.x] == 0 ? -1 : (countDots - d[goal.y][goal.x]));
	}
}